SENDAI, Japan (AP) — The estimated death toll from Japan's disasters climbed past 10,000 Sunday as authorities raced to combat the threat of multiple nuclear reactor meltdowns and hundreds of thousands of people struggled to find food and water. The prime minister said it was the nation's worst crisis since World War II.(SCROLL DOWN FOR LIVE UPDATES)Nuclear plant operators worked frantically to try to keep temperatures down in several reactors crippled by the earthquake and tsunami, wrecking at least two by dumping sea water into them in last-ditch efforts to avoid meltdowns.